A Study on the Conductive Particle Movements in Polyvinylidene Fluoride Anchoring Polymer Layer Anisotropic Conductive Films for 20- $\mu$ m Fine-Pitch Interconnection

Fine-pitch interconnection technology in electronic packaging has become very important because of electrical interconnection issues such as high contact resistance and open-/short-circuit failure. Nanofiber anisotropic conductive films (ACFs) and nanofiber sheet ACFs (NS ACFs) have been developed and reported by our research group to address the challenges for fine-pitch interconnection problems. However, they require complicated fabrication processes such as electrospinning, thermal compression, and plasma etching. In this paper, anchoring polymer layer (APL) ACFs and their fabrication process are introduced. The goal in employing the APL ACFs was to simplify the complex fabrication steps of nanofibers and NS ACFs by coating methods without compromising electrical performance. With the APL coating method, the electrospinning, thermal compression, and plasma etching steps can be reduced to a single process. Nonetheless, APL ACFs exhibit excellent electrical conduction at 20-μm fine-pitch interconnections by successfully suppressing the movement of conductive particles in the ACF. The capture rate of the APL ACFs was 78%, which was comparable to the value 81% of NS ACFs. APL ACFs open the possibility of cost-effective production of ACFs interconnection materials for fine-pitch applications. Therefore, we use the word “anchoring” to suppress the movement of conductive particles during resin flow. In this paper, we discuss the fabrication process of APL structure and electrical properties of APL ACFs.